1. Field of the Invention
This invention is in the field of chemical reactor machines for reacting one or more solid reactants with one or more gaseous reactants.
2. Description of the Prior Art
Prior art chemical reactor machines for reacting solid reactants with gaseous reactants are operated at essentially steady and usually low pressures with the results that useful work output cannot be generated directly and continuously from any heat of the gas to solid reaction and the reactions are slow since essentially only the external surface area of the solid particles is utilized for carrying on the reaction. Additionally, prior art solid to gas reactor machines mix the solid reactants together, where two or more solid reactants are used, so that reaction may occur between the solid reactants and produce undesired results.
To produce mechanical work directly and continuously from a gas to solid chemical reaction requires use of a work cycle or a work process wherein high gas pressures prevail during a portion of the cycle or process and low gas pressures prevail during another portion of the cycle or process. The work quantity generated per unit of chemical reaction increases generally with increasing differences between the high pressures and the low pressures. Hence, steady pressure reaction processes, as now used for gas to solid reactions, cannot produce continuous work output directly from the reaction process and this is a deficiency of prior art steady pressure solid to gas chemical reactor machines.
Gas to solid chemical reactions necessarily take place upon the solid surface and the rate of reaction is proportional to the area of solid exposed to gas and also the concentration of gas reactant adjacent to that area. Product gases formed from the solid to gas reaction tend to remain adjacent the solid area from which they were formed and thus act to "blanket" the solid area by reducing the concentration of gas reactant adjacent that area. In this way the product gas blanket acts to slow down the solid to gas reaction. This product blanket retardation is especially strong inside dead-end pore spaced of a solid reactant at steady pressures since the product blanket gases can only be removed by slow diffusion out through the long pore passage and fresh gas reactant can reach these interior pore surface areas only by slow counter diffusion through the same long pore passage. Hence, for steady pressure reactors the interior pore spaces of a solid reactant are poorly utilized for carrying on reaction with a gas reactant and the principal reaction occurs only on the external surface area of the solid where the diffusion paths for product blanket removal and fresh gas reactant replacement are short. It is a common practice in prior art, steady pressure, solid to gas reactors to further shorten these external solid area diffusion path lengths by forcing the gas reactant through the solid reactant flow passages at high velocity to thin down the stagnant gas boundary layer on these areas. But such high velocity flow produces a pressure loss requiring a work input to sustain the process. These are additional deficiencies of prior art steady pressure solid to gas reactors, that the dead end pore spaces are little used for carrying on the reaction, and a work input is usually needed to achieve reasonable reaction rates on the external solid areas being actually utilized.
Some solid reactants have little or no dead-end pore spaces but many solid reactants, particularly naturally occurring minerals such as coal and metal ores, have internal pore spaces. Commonly the solid area within these interior pore spaces is many fold greater than the external surface area of the solid reactant. A reactor capable of efficiently using both the external area and the interior pore area of a solid reactant could carry out solid to gas reactions much faster than prior art steady pressure reactors.
Where two or more solid reactants are to react jointly with one or more gas reactants in a steady pressure reactor, it is usually necessary to premix the solid reactants in order that they be in close proximity to one another so that the joint reaction with the gases can take place. In a blast furnace, for example, air is reacted jointly with coke and iron ore, the oxygen reacting with coke to form carbon monoxide, the carbon monoxide reacting with iron ore to form iron and carbon dioxide, and the carbon dioxide, in turn, reacting with coke to return to carbon monoxide again. The coke and iron ore must be reasonably close together if this process is to be carried out. But inevitably the iron product also reacts with the adjacent coke to form iron carbides and dissolved carbon and this carbon must then be later removed from the pig iron product of the blast furnace in another separate reactor in order to produce a final steel product. A solid to gas reactor wherein two or more solid reactants can be kept separated and yet can react jointly with one or more gas reactants would permit carrying out these reactions without incurring such undesirable solid to solid reactions.
In prior art steady pressure solid to gas reactors the gas is passed but one over the solid and thus either poor utilization of the gas reactant results or else the solid reactant must be in a deep bed requiring appreciable work input to force the gas therethrough. This is an additional deficiency of prior art solid to gas reactors.
The term solid reactant is used herein and in the claims to include wholly solid materials as well as solids whose surface is wetted with a liquid. A single separate solid reactant can be but a single chemical or a mixture of several chemicals. Separate solid reactants are materials kept mechanically separated and not mixed together. Solid reactants are delivered into a reactor.
The term gas reactor is used herein and in the claims to include single gaseous chemicals as well as mixtures of several different gaseous chemicals. Separate gas reactants are gases kept mechanically separated and not mixed together. A gas reactant may be chemically unreactive or inert with a solid reactant as, for example, a purge gas used to remove a previously used gas which was reactive with the solid reactant. Gas reactants are delivered into a reactor.
The term product gas is used herein and in the claims to include single gases or mixtures of gases. Separate product gases are gases kept mechanically separated and not mixed together. Gas products are discharged out of a reactor.
The term non gas product is used herein and in the claims to include solids, liquids and mixtures of solids and liquids. Separate non gas products are kept mechanically separated and are not mixed together. Non gas products are discharged out of a reactor.
The term compressor means is used herein and in the claims to mean a combination comprising a positive displacement compressor expander element, a delivery means for delivering gases into the compressor expander element from a reactant gas inlet pipe, and a power means to drive the compressor expander element and to absorb any work output of the compressor expander element. The compressor expander element can be any of the positive displacement types well known in the prior art as, for example, the following:
The delivery means can be any of the delivery valves in common use on prior art positive displacement compressor expander units such as mechanically driven valves, hydraulically driven valves, pneumatically driven valves, electrically driven valves, etc. A delivery means opens for reactant gas delivery only during a delivery process and is sealed by a sealing means at other times. The power means can be any of the various drive means and power absorbing means already well known in the prior art as, for example, the following:
The power means can be a single unit or at least two units, one for driving and one for power absorbing. In most cases, the compressor means will additionally comprise a discharge means for discharging gases from the compressor expander element into a product gas output pipe. The discharge means can be similar to the above-described delivery means except arranged for discharge. A discharge means opens for product gas discharge only during a discharge process and is sealed by a sealing means at other times. A positive displacement compressor expander compresses or discharges during volume decreasing motions of the mechanism and expands or delivers during volume increasing motions of the mechanism. A single compressor means comprises but a single compressor expander element. A reactor plant may comprise several compressor means and hence several compressor expander elements and, if desired, these several compressor means can be mechanically connected together and to but a single power means.
The term piston and cylinder is used herein to mean these elements as commonly used in piston and cylinder compressor expander units and the functionally equivalent portions of other types of compressor expander units.